Abrasive article



' resistant to these pasta James, 1921.

UNITED] STATES I PATENT OFFICE.-

II'NEB I mm, 01 NIAGARA FALLS, NEW YORK, ABSIG IIOB 1'0 m GLRBO- BUNDUI COMPANY, OI NIAGABA. I'ALLB, mm YORK, A OOBPOMTION mmvmra.

Io Drawing.

This invention relates to an improvement in abrasive articles; In then"- usual form, Q abrasive articles are made up of hard particles: of crystalline. mineral material, such 4 as silicon carbide, emery, fused alummay and aluminous materials commonly known in the trade as aloxite, alundum, and the like, held together by bonding agents, such as fused silicates, glue, shellac, rubber, redmanol, Portland cement, magnesium oxychloride cement, etc.

I have discovered that certain defects of abrasive articles may be obviated or lessened ation of the abrasive article r and the like, which in many cases are not sufiiciently strong for certain abrasive operations, are so much strenhened by of the articles sul hur that they may be successfull I used or example, in the A abrasion 0 soft or malleable materials, such as aluminum or copper, the sulphur revents the stickingof the abraded materia s in the res of the abrasive wheel or artic1e, t here- I {inventing the decrease in cutting q 'ty of the abrasive article. Abrasive appliances made from abrasivegrain and.

' bonding-materials .which are not sufliciently resistant. to water or other liquids used in ding operations, may be'made entirel grin liflluids by the usejof thi s invention, that is, e imlpregnationof the articles by elementary su phur. In certain grinding operations, suchas polishing of marble or of stone, the abrading action ea may be softened by. the impregnation of the wheel or rubbing stone' with sulphur, Asan illustration of the method of using this invention I may use, for exam le, an abrasive wheel made by bonding car runl0 dum grains with fused silicate. This wheel is immersed in'a bath-of'molten elementary sulphur which is allowed to come to the temperature at which the sulphur liquid. As is well known, sulphur, when the impregnation,

Application and [arch '14, 1,924. (semi s6. 009,310.

heated, first melts, becomes quite liquid, then as the temperature increases becomes viscous, after.which it again becomesvery liq-- uid. Either of these ranges of high fluidity may be employed for the impregnation of the abrasive articles. ,By the immersion and heating ofthe article in this manner in molten sulphur, I have found that the air entrapped in the pores of the article is re-.

moved andv that the sulphur penetrates through the article. With very dense articles, however, it might be necessary to emmy invention contemplates t is ste where required. After the bath has coole sufiicient-ly to solidify the sulphur within a vacuum to remove the entrapped air the,,excess sulphur taken of! by any coni familiar manner of grinding appliances. Such a wheel may be used .ve successfully for the grinding of soft meta s which tend to clog up or fill the) penetranot limit my invention to-cooling the. bath to solidify' the sulphur in the pores of the 7 article inQthe air 6r by subjecting itto the action of a cooling medium.

Various other wellknown abrasive arti-f cles may be improved by the use ofsulphur in. the manner described. As another example, Portland cement has been used to some extent as a bond' for abrasive grains,

I but it has usually been found to be too weak for most grinding operations: By the impregnation with sulphur of a Portland cement bonded abrasive wheel in the manner described above, Ihave-found that the me venient means and the wheel used in the pores of the wheel. The presence of the sulphur inthe pores of the abrasive article prevents this tion and sticking by the'soft metals. I do chanical properties of the wheel are so 1 greatly im roved that such a" wheel may be used for t e grinding ofwood pulp for paper. a J

While I have described only two of the possible applications of my invention, I do not limit myself to these examples, but may use this invention to improve any kind of abrasive article by impregnation thereof with sulphur.

1o 7 the pores of the wheel, the latter isremoved, Y

I claim:

1: An artificial granular abrasive article" composed of abrasive grains and'a binder alllld having the pores thereof filled with sul p 2. An artificial abrasive comprised of a porous mass of abrasive grains and an inorganic binder and having the pores thereof filled with sulphur.

3. An artificial abrasive consisting of abrasive grains bonded with Portland cement and having ,the interstices thereof filled with elementary sulphur.

4. In a method of improving a formed porous abrasive article held together by an inorganic bonding agent, the step consisting in impregnating said article with sulphur.

5. In a method of improving a porous abrasive article held together by an inorganic bonding agent, the steps consisting in immersing said article in molten sulphur, raising the temperature of the sulphur to drive out air in the article whereby the interstices in the article will be filled with sulphur, the sulphur being maintained during at least part of the operation at a temperature where it is fluid, removing the article from the sul hur, and cooling the article to solidify t e sulphur in the pores' thereof.

6. The method of improving an abrasive article composed of abrasive grains held together by a bonding material, comprising immersing said article in a: bath of molten sulphur at a temperature suflicient to remove the air entrapped in the pores of the article and allow said pores to fill with' the molten sulphur, and solidifying. the sulphur within the pores of the abrasive article by cooling.

7 The method of improving an abrasive article composed of abrasive grains held together by an inorganic binding material, comprising immersing said article in a bath of molten sulphur at a temperature suificient to remove the air entrapped in the pores of .the article and allowing said pores to fill with the molten sulphur, allowing the bath to cool to solidify the sulphur within the pores of the abrasive article, and then removing the article from the bath and removing excess sulphur therefrom.

In testimony whereof I have hereunto set my hand.

MINER L. HARTMANN. 

